spamassassin report spam header

Hello !!
Do anyone know how can I configure spamassassin to write “spam report” into header to be able to analize why some emails are identifify as spam or ham?
I’ve got a server running Centos 5 and spamassassin 3.3.1 with sendmail 8.13 and procmail, Webmin and Virtualmin GPL at the last release.
Thanks a lot !!